wassx
Member
@igor:
thanks for asking! I'm still in the race. Little bit stressy at the moment.
-stef
thanks for asking! I'm still in the race. Little bit stressy at the moment.
-stef
Official 33609 builder's tread. See 1st page for updates.
- Thread starter Igor
- Start date
Help Support GroupDIY Audio Forum:
Amnezia
Member
[quote author="promixe"][quote author="Amnezia"]
Maybe i'm just stupid.. but what is "PLS"?... [/quote]
"PLS x'plain" in this case, I think, refers to "Please explain" =)
From your previous post:
I think somehow you are confused that on the PCB silkscreen the outlines for those two resistors (R23 & R41) look somewhat bigger than the rest of the resistor outlines on the board. If this is your concern - those resistors should be no different in size or wattage, just make sure they are the right values (as it is printed right on the board and in the BOM)...[/quote]
Hi man.. thanks alot.. it was exactly what I was thinking.. I was looking at the PCB.. and some pictures of Igor's finished unit.. and it did not seem like "normal" metal resistors.. so I got confused.. Thanks for clearing that out.. :thumb:
The resistors for the elma's .. they are confusing me a little too.. in the BOM it seems that I should use other values.. but on the PCB there are other values again..
As long as I make sure only resistors with the values wrote on the PCB get attacked.. I'll be fine?..
(Looking away from the BOM some few times.. and just focus on the values on the PCB)... right?.. :?
Maybe i'm just stupid.. but what is "PLS"?... [/quote]
"PLS x'plain" in this case, I think, refers to "Please explain" =)
From your previous post:
I personally only understood the word "BOM" =) So, all this means, you have to explain what you are trying to ask more clearly, because so far none of us can't understand what you mean, and therefore we are unable to help.
I think somehow you are confused that on the PCB silkscreen the outlines for those two resistors (R23 & R41) look somewhat bigger than the rest of the resistor outlines on the board. If this is your concern - those resistors should be no different in size or wattage, just make sure they are the right values (as it is printed right on the board and in the BOM)...[/quote]
Hi man.. thanks alot.. it was exactly what I was thinking.. I was looking at the PCB.. and some pictures of Igor's finished unit.. and it did not seem like "normal" metal resistors.. so I got confused.. Thanks for clearing that out.. :thumb:
The resistors for the elma's .. they are confusing me a little too.. in the BOM it seems that I should use other values.. but on the PCB there are other values again..
As long as I make sure only resistors with the values wrote on the PCB get attacked.. I'll be fine?..
(Looking away from the BOM some few times.. and just focus on the values on the PCB)... right?.. :?
promixe
Well-known member
Which version of BOM are you using? The only thing I've noticed is that the 120R resistor on LIM_THR (Elma board) is missing in EVERY BOM out there... So, make sure you order that one, otherwise you're gonna be missing a position =)
Also, R31 is 680R on the board, but in the schematic it's 560R... Those are the only things I've found with BOMs (I'm using 680R for R31, as is in everyone's BOMs)...
maxheadroom
Well-known member
i have a small question about the sifam knobs,
does anybody know the part number of these knobs?
thanks!!
does anybody know the part number of these knobs?
thanks!!
promixe
Well-known member
[quote author="maxheadroom"]i have a small question about the sifam knobs,
does anybody know the part number of these knobs?
thanks!![/quote]
Depends on what look you're going after. =) JdJ and I went after the 21mm knobs (I liked the way his unit looked on page #17 of this thread and got the same knobs). The part # for these knobs is S210-250GRAY (which is 21mm light gray knobs with no pointer). And the caps are: C211BLUE/9 (21mm blue caps with white pointer).
However, if you're going after the look of the modern original 33609JD version - you will probably be better off getting 15mm knobs/caps (just use S15 and C15 in the part #s instead of S21/C21).
Word of warning: I had trouble fitting these 6mm collet knobs onto Lorlin switches - the switch shaft is too narrow and the collet slips on it even if you tighten it all the way to the max. I had to melt the shafts and hack the knob onto them in a non-pleasant time consuming way =) But you could never tell visually that there was such an obstacle. Anyone else can confirm this problem?
does anybody know the part number of these knobs?
thanks!![/quote]
Depends on what look you're going after. =) JdJ and I went after the 21mm knobs (I liked the way his unit looked on page #17 of this thread and got the same knobs). The part # for these knobs is S210-250GRAY (which is 21mm light gray knobs with no pointer). And the caps are: C211BLUE/9 (21mm blue caps with white pointer).
However, if you're going after the look of the modern original 33609JD version - you will probably be better off getting 15mm knobs/caps (just use S15 and C15 in the part #s instead of S21/C21).
Word of warning: I had trouble fitting these 6mm collet knobs onto Lorlin switches - the switch shaft is too narrow and the collet slips on it even if you tighten it all the way to the max. I had to melt the shafts and hack the knob onto them in a non-pleasant time consuming way =) But you could never tell visually that there was such an obstacle. Anyone else can confirm this problem?
FLOATING ISSUES SOUNDCARD FLUKE ETC MEASURING EXPLAINED HERE
It took me some time to understand what is going on with your measures.
First, your souncard probably balanced _and_ not floated
(dunno any soundcard with trafocoupled output
THEN
When you refer to soundcard output level,
measure with AC voltmeter beetween T2 pri+ and pri-,
only this is relevant....
because if measurement done on pri+ to gnd and there's 0.775v
and pri- to gnd (same 0.775V) it is actually 1.55V on primary of T2!!!!
I.e. you feed actually +6 db....
Then.
Same thing with pri of T1...
You need to refer to AC voltmeter's reading beetween
T2PRI+ and T2 PRI-.....
Then, when measuring on secondary of T1, it's - fortunately
connected to GND, all seems right....
And, if measurement was done T3+ to gnd, it was wrong...
because T3- was floated....
T3's wrong ratio:
Please measure T3SEC- to T3SEC+ with AC voltmeter,
should be 0db when between TP_D and gnd there's -8dB....
))
For good start,
Just ground sec- of T3, and feed 0.775V beetween T2 pri+/T2pri-....
Just.....remember, these freaky trunny's are floated.
It is actually two chokes coupled with magnetic field.
They don't know what is ground if no connection to ground...
For me it is easy to talk, 'cause I have an analyser with balanced in/out
(well, it is not allways balanced, there's button "float" on in/out).....
So, just please measure with AC voltmeter as above, and tell..
When measuring with scope output of T3, just connect sec- to gnd.
Good luck!
I have a feel everyhing is OK with this unit
Sorry again for my dead english
OK
It took me some time to understand what is going on with your measures.
First, your souncard probably balanced _and_ not floated
(dunno any soundcard with trafocoupled output
THEN
When you refer to soundcard output level,
measure with AC voltmeter beetween T2 pri+ and pri-,
only this is relevant....
because if measurement done on pri+ to gnd and there's 0.775v
and pri- to gnd (same 0.775V) it is actually 1.55V on primary of T2!!!!
I.e. you feed actually +6 db....
Then.
Same thing with pri of T1...
You need to refer to AC voltmeter's reading beetween
T2PRI+ and T2 PRI-.....
Then, when measuring on secondary of T1, it's - fortunately
connected to GND, all seems right....
And, if measurement was done T3+ to gnd, it was wrong...
because T3- was floated....
T3's wrong ratio:
Please measure T3SEC- to T3SEC+ with AC voltmeter,
should be 0db when between TP_D and gnd there's -8dB....
))For good start,
Just ground sec- of T3, and feed 0.775V beetween T2 pri+/T2pri-....
Just.....remember, these freaky trunny's are floated.
It is actually two chokes coupled with magnetic field.
They don't know what is ground if no connection to ground...
For me it is easy to talk, 'cause I have an analyser with balanced in/out
(well, it is not allways balanced, there's button "float" on in/out).....
So, just please measure with AC voltmeter as above, and tell..
When measuring with scope output of T3, just connect sec- to gnd.
Good luck!
I have a feel everyhing is OK with this unit
Sorry again for my dead english
promixe
Well-known member
Hey guys! Quick and dirty update:
Igor: I KNEW I WAS DOING THIS WRONG =) Anyway... When I measured stuff like you suggested everything checked out perfect in terms of audio path ratios etc. However, when calibrating limiter/compressor sections I still couldn't match the parameters specified in the test procedures... More on that later, I can't think at the moment =)
Next: I didn't have enough patience, I calibrated the boards as close as I could, made sure they were even relatively to themselves. I brought the very original 33609, set it on top of my newly baked one =) Hooked it up and started listening (finally!) =)
So far I'm disappointed, but I believe this still might be incorrect calibration + some components responsible for release/attack times. Basically, my initial quick and dirty conclusion is my compressor is way too fast comparing to the original. Here are some audio files:
http://dev.ax-design.com/electronics/33609/33609-test1.mp3 - dry sample (yes, I know it's already compressed too much, not an ideal test material, blah blah =) But it's even more interesting and harsh scenario for the compressors to undergo.
http://dev.ax-design.com/electronics/33609/33609-test2.mp3 - My 33609. Low end is distorting a lot... Sounds like it's releasing too fast, attacking too fast as well (especially).
http://dev.ax-design.com/electronics/33609/33609-test3.mp3 - The original. Silky and smooth. Same signal, SAME LEVELS fed into it, SAME SETTINGS are dialed in. See pics for settings. I've used pretty unreal squashy setting for this test, but the original still behaves like the classic =)
I deliberatly left some empty space at the beginning of the processed files to capture the noise floor of each unit. They seem pretty similar loudness wise, with mine being slightly closer to full white spectrum, and the original having a little mid-rangy character to it.
Pics:
I think this will be pretty interesting, as noone so far has posted real audio examples / real comparisons with original 33609s here...
This is just the beginning =) I'm gonna fully test stuff tomorrow, I've got until monday afternoon to play with the original =)
Igor, thanks again for your clarifications man!
Igor: I KNEW I WAS DOING THIS WRONG =) Anyway... When I measured stuff like you suggested everything checked out perfect in terms of audio path ratios etc. However, when calibrating limiter/compressor sections I still couldn't match the parameters specified in the test procedures... More on that later, I can't think at the moment =)
Next: I didn't have enough patience, I calibrated the boards as close as I could, made sure they were even relatively to themselves. I brought the very original 33609, set it on top of my newly baked one =) Hooked it up and started listening (finally!) =)
So far I'm disappointed, but I believe this still might be incorrect calibration + some components responsible for release/attack times. Basically, my initial quick and dirty conclusion is my compressor is way too fast comparing to the original. Here are some audio files:
http://dev.ax-design.com/electronics/33609/33609-test1.mp3 - dry sample (yes, I know it's already compressed too much, not an ideal test material, blah blah =) But it's even more interesting and harsh scenario for the compressors to undergo.
http://dev.ax-design.com/electronics/33609/33609-test2.mp3 - My 33609. Low end is distorting a lot... Sounds like it's releasing too fast, attacking too fast as well (especially).
http://dev.ax-design.com/electronics/33609/33609-test3.mp3 - The original. Silky and smooth. Same signal, SAME LEVELS fed into it, SAME SETTINGS are dialed in. See pics for settings. I've used pretty unreal squashy setting for this test, but the original still behaves like the classic =)
I deliberatly left some empty space at the beginning of the processed files to capture the noise floor of each unit. They seem pretty similar loudness wise, with mine being slightly closer to full white spectrum, and the original having a little mid-rangy character to it.
Pics:
I think this will be pretty interesting, as noone so far has posted real audio examples / real comparisons with original 33609s here...
This is just the beginning =) I'm gonna fully test stuff tomorrow, I've got until monday afternoon to play with the original =)
Igor, thanks again for your clarifications man!
Release: please check 8k2/24k issue...
(there's some words on this tread)
cal procedure
etc
Maybe still some things in your unit swaped or wrong...
We compared clone built with Beclaire's/Marinair output
to original 33609, it was very close soundwise.
BTW, I rember, original was a bit out of calibration,
one channel had lower threshold (by 1-2 db or so),
anyway....still very close in sound.
I think, this is one of your first experiments
with complicated pro' stuff ladies.
Patience, care and attension is the best strategy
I had some previous experience with analog electronics from
medical stuff, like lasers and ultrasound.
Here, allmost all things written on paper..
Horowitz/Hill's patterns in different combinations.
Then, after building some tens (or more) of clones
of everything possible from 1072, 1176, mixbuzz, Sontec,
QE, to 1081, 33609, etc,
than some tens of protos of my own stuff including design
of whole mixing deck, I understood that pro audio is absolutely
freaky separeted field of electronics, different at all, sometimes
even fully absurd...but it has it's own "tao".
And a lot of thing are in "grey arrea"....
Lot of things are coming only from experience.
I allways happy to learn something new in "tao of audiotronics"...
Just continue with 33609 slowly, it is perfect way to learn.
Probably you'll find some points...
BTW, if there's guys who have fully calibrated working units
it will be interesting to compare sound samples of different trunnies, etc.
(there's some words on this tread)
cal procedure
etc
Maybe still some things in your unit swaped or wrong...
We compared clone built with Beclaire's/Marinair output
to original 33609, it was very close soundwise.
BTW, I rember, original was a bit out of calibration,
one channel had lower threshold (by 1-2 db or so),
anyway....still very close in sound.
I think, this is one of your first experiments
with complicated pro' stuff ladies.
Patience, care and attension is the best strategy
I had some previous experience with analog electronics from
medical stuff, like lasers and ultrasound.
Here, allmost all things written on paper..
Horowitz/Hill's patterns in different combinations.
Then, after building some tens (or more) of clones
of everything possible from 1072, 1176, mixbuzz, Sontec,
QE, to 1081, 33609, etc,
than some tens of protos of my own stuff including design
of whole mixing deck, I understood that pro audio is absolutely
freaky separeted field of electronics, different at all, sometimes
even fully absurd...but it has it's own "tao".
And a lot of thing are in "grey arrea"....
Lot of things are coming only from experience.
I allways happy to learn something new in "tao of audiotronics"...
Just continue with 33609 slowly, it is perfect way to learn.
Probably you'll find some points...
BTW, if there's guys who have fully calibrated working units
it will be interesting to compare sound samples of different trunnies, etc.
keithcamilleri
Well-known member
- Joined
- Jun 5, 2004
- Messages
- 119
hi guys i am using carnhill iron for this project.
I am having a little trouble wiring the xformers, take vtb9046 for example do you connect pin 2 to primary negative ( short 3 and 4 ) and connect pin 5 to primary positive? is that the right way to go by?
http://www.audiomaintenance.com/downloads/carnhill_design_guide.pdf
thanks
keith
I am having a little trouble wiring the xformers, take vtb9046 for example do you connect pin 2 to primary negative ( short 3 and 4 ) and connect pin 5 to primary positive? is that the right way to go by?
http://www.audiomaintenance.com/downloads/carnhill_design_guide.pdf
thanks
keith
promixe
Well-known member
[quote author="keithcamilleri"]hi guys i am using carnhill iron for this project.
I am having a little trouble wiring the xformers, take vtb9046 for example do you connect pin 2 to primary negative ( short 3 and 4 ) and connect pin 5 to primary positive? is that the right way to go by?
http://www.audiomaintenance.com/downloads/carnhill_design_guide.pdf
[/quote]
One page back:
Also page #20 of this thread has info on this. If you wire pin2 to negative, make sure pin7 goes to negative secondary, just so you don't swap the phase. I wired pin2 to positive (pin 7 positive as well) because the drawing shows phase "dots" at those pins.
I am having a little trouble wiring the xformers, take vtb9046 for example do you connect pin 2 to primary negative ( short 3 and 4 ) and connect pin 5 to primary positive? is that the right way to go by?
http://www.audiomaintenance.com/downloads/carnhill_design_guide.pdf
[/quote]
One page back:
Also page #20 of this thread has info on this. If you wire pin2 to negative, make sure pin7 goes to negative secondary, just so you don't swap the phase. I wired pin2 to positive (pin 7 positive as well) because the drawing shows phase "dots" at those pins.
Underthebigtree
Well-known member
Hi guys -
I'm getting tantalizingly close with my unit, but hung up at the calibration procedure.
The unit is passing audio, but I'm having trouble with the metering during the diode bridge calibration (section 4). I can get the outputs adjusted properly by:
* assigning a 0dB 1kHz sin wave to the input,
* setting the CV voltage to 3 volts,
* setting the master bypass to the 'in' position
* attaching an alligator clip from the +CV in on the PS board to the link pin on the main board, right next to BC184
* tweaking RV2 to get -8dB at the output
* then readjusting R6 on PS board to get -20dB at output
No matter what, though, the meter becomes pinned as soon as I attach the alligator clip. I thought that the meter needed a 3K6 resistor (which it probably does, right?) which I added, but no change.
Any ideas?
Thanks,
Nick
I'm getting tantalizingly close with my unit, but hung up at the calibration procedure.
The unit is passing audio, but I'm having trouble with the metering during the diode bridge calibration (section 4). I can get the outputs adjusted properly by:
* assigning a 0dB 1kHz sin wave to the input,
* setting the CV voltage to 3 volts,
* setting the master bypass to the 'in' position
* attaching an alligator clip from the +CV in on the PS board to the link pin on the main board, right next to BC184
* tweaking RV2 to get -8dB at the output
* then readjusting R6 on PS board to get -20dB at output
No matter what, though, the meter becomes pinned as soon as I attach the alligator clip. I thought that the meter needed a 3K6 resistor (which it probably does, right?) which I added, but no change.
Any ideas?
Thanks,
Nick
promixe
Well-known member
Igor, pardon my ignorance, but how do you measure attack/release times/slopes with the scope? I looked through all the pictures on page 1 of this thread where you display scope shots with various attack/release conditions and I would like to verify my unit against them.
Do I send in a 0dBu 1k sine and measure at the output or elsewhere?
I guess the main and more general question is: how to measure (fairly precisely) compressor/limiter response and recovery times in milliseconds?
Thanks!
PS: Also, I'm getting a weird behavior when I switch the bypass OUT - the stereo image severely shifts (one channel louder than the other)... It wasn't that way when I was calibrating... hmm...
Do I send in a 0dBu 1k sine and measure at the output or elsewhere?
I guess the main and more general question is: how to measure (fairly precisely) compressor/limiter response and recovery times in milliseconds?
Thanks!
PS: Also, I'm getting a weird behavior when I switch the bypass OUT - the stereo image severely shifts (one channel louder than the other)... It wasn't that way when I was calibrating... hmm...
promixe
Well-known member
UPDATE: Ok! After more careful and systematic listening for attack/release issues I notice the following:
- Compressor sounds good except when switching to 100ms recovery. Then it starts sounding really grainy/distorted. Sounds like it might be R10 issue (i e 6K8 needs swapped for 24K). Has ANYONE noticed this behavior when using 6k8 resistor there or am I the only one? Has anyone used 24k there instead of the specified 6k8?
- R31 is 560R in the schematic but is labeled 680R on the board (see a couple of pages ago I mentioned it). This seems to be the resistor responsible for attack time. Correct me if I'm wrong though, but swapping it for 560R is going to make the attack FASTER?
- Limiter is where things start sounding really bad. The issue seems to be with the attack set to FAST. When it is at fast position everything sounds really distorted (horrible) especially in the low end. This seem to gradually disappear with increasing limiter recovery time. It is really pronounced and heavily distorted at 50 and 100ms settings, but starts to go away gradually at 200ms and up.
- with the attack switched to SLOW things sound somewhat grainy only at 50ms. The original 33609 I had over the weekend seemed to behave similarly in this scenario. When recovery switched to 100ms and up things sound smoother (normal).
I've checked R28 & R30 responsible for the attack selection on the limiter, they are both dead on 1k6 as specified. C14 is good too.
Clues/ideas? =)
UPD: Just swapped 6k8 for 24k on one of the channels - grainy stuff went away noticeably!!! Although I can still hear it it sounds more like the original 33609 in this aspect... Now I need to figure out the limiter section...
- Compressor sounds good except when switching to 100ms recovery. Then it starts sounding really grainy/distorted. Sounds like it might be R10 issue (i e 6K8 needs swapped for 24K). Has ANYONE noticed this behavior when using 6k8 resistor there or am I the only one? Has anyone used 24k there instead of the specified 6k8?
- R31 is 560R in the schematic but is labeled 680R on the board (see a couple of pages ago I mentioned it). This seems to be the resistor responsible for attack time. Correct me if I'm wrong though, but swapping it for 560R is going to make the attack FASTER?
- Limiter is where things start sounding really bad. The issue seems to be with the attack set to FAST. When it is at fast position everything sounds really distorted (horrible) especially in the low end. This seem to gradually disappear with increasing limiter recovery time. It is really pronounced and heavily distorted at 50 and 100ms settings, but starts to go away gradually at 200ms and up.
- with the attack switched to SLOW things sound somewhat grainy only at 50ms. The original 33609 I had over the weekend seemed to behave similarly in this scenario. When recovery switched to 100ms and up things sound smoother (normal).
I've checked R28 & R30 responsible for the attack selection on the limiter, they are both dead on 1k6 as specified. C14 is good too.
Clues/ideas? =)
UPD: Just swapped 6k8 for 24k on one of the channels - grainy stuff went away noticeably!!! Although I can still hear it it sounds more like the original 33609 in this aspect... Now I need to figure out the limiter section...
wassx
Member
Ladies and Gentlemen!
My neve works.
:sam:
Just tested the two boards, and... oh yeah, I'm sitting here writing with a smile on my face.
My problem was, terrible as it can be, the cables to the frontpanels. Instead of the shield I splitted the cable to the two pins. A absolutly classical nonsense. (I think I passed point one on Igor's list. Put the right record on your turntable :wink: )
So I want to say "Thank you" to:
Chrisotop, who managed all the part ordering and helped me out with my problem
Igor, for this great project and help (I'm a noob, so you can guess how proud I am now)
To all people discussing their work in this forum, giving me a lot of hints
THANK YOU
I'm going back to work, some case work is missing and the knobs as well.
My neve works.
:sam:
Just tested the two boards, and... oh yeah, I'm sitting here writing with a smile on my face.
My problem was, terrible as it can be, the cables to the frontpanels. Instead of the shield I splitted the cable to the two pins. A absolutly classical nonsense. (I think I passed point one on Igor's list. Put the right record on your turntable :wink: )
So I want to say "Thank you" to:
Chrisotop, who managed all the part ordering and helped me out with my problem
Igor, for this great project and help (I'm a noob, so you can guess how proud I am now)
To all people discussing their work in this forum, giving me a lot of hints
THANK YOU
I'm going back to work, some case work is missing and the knobs as well.
promixe
Well-known member
UPDATE: Ok, here is how the calibration goes:
5.2
When I calibrate RV5 to get -16dBu at the output with comp THD set to -20, then at THD set to 0 the output reads -1.2dBu...
When I calibrate RV5 to get -1dBu at the output with comp THD set to -2, then at THD set to 0 the output reads -0.2dBu... With the same RV5 position when I switch THD to -20, the output reads -14.14dBu... Would this be considered within normal behavior? Should I calibrate both boards like this? This seems to be the closest of both worlds (I mean a relatively okay balance between opposite THD settings)...
There is no way to accommodate every setting of the calibration to match the figures that are specified in the procedure...
4.2
Applying +16.3dBu to the input. RV4 calibrates fine for +4dBu output at +4 THD. However the output level starts gradually drifting as I increase THD and by the time it's at +13 the output is 0.5dB off (reads +12.5dBu). Would this be normal?
Also, when I switch attack from FAST to SLOW, the +4dBu output increases by +0.14dB - is this okay or should the level stay unaffected?
And then questions from my previous posts remain relevant:
- R31 is 560R in the schematic but is labeled 680R on the board (see a couple of pages ago I mentioned it). This seems to be the resistor responsible for attack time. Correct me if I'm wrong though, but swapping it for 560R is going to make the attack FASTER?
- Limiter is where things start sounding really bad. The issue seems to be with the attack set to FAST. When it is at fast position everything sounds really distorted (horrible) especially in the low end. This seem to gradually disappear with increasing limiter recovery time. It is really pronounced and heavily distorted at 50 and 100ms settings, but starts to go away gradually at 200ms and up.
- with the attack switched to SLOW things sound somewhat grainy only at 50ms. The original 33609 I had over the weekend seemed to behave similarly in this scenario. When recovery switched to 100ms and up things sound smoother (normal).
- how to measure (fairly precisely) compressor/limiter response and recovery times in milliseconds? How to make the slopes visual on the analog scope without any special equipment?
PS: swapped R10 from 6k8 to 24k - seems to have solved the issue of the compressor sounding grainy at 100ms recovery.
Igor, thanks for your help man! I think I'm very close to have solved all of the issues with my unit (half of which are probably my misunderstandings of electronics and not knowing tolerances of calibration ) =)[/code]
5.2
When I calibrate RV5 to get -16dBu at the output with comp THD set to -20, then at THD set to 0 the output reads -1.2dBu...
When I calibrate RV5 to get -1dBu at the output with comp THD set to -2, then at THD set to 0 the output reads -0.2dBu... With the same RV5 position when I switch THD to -20, the output reads -14.14dBu... Would this be considered within normal behavior? Should I calibrate both boards like this? This seems to be the closest of both worlds (I mean a relatively okay balance between opposite THD settings)...
There is no way to accommodate every setting of the calibration to match the figures that are specified in the procedure...
4.2
Applying +16.3dBu to the input. RV4 calibrates fine for +4dBu output at +4 THD. However the output level starts gradually drifting as I increase THD and by the time it's at +13 the output is 0.5dB off (reads +12.5dBu). Would this be normal?
Also, when I switch attack from FAST to SLOW, the +4dBu output increases by +0.14dB - is this okay or should the level stay unaffected?
And then questions from my previous posts remain relevant:
- R31 is 560R in the schematic but is labeled 680R on the board (see a couple of pages ago I mentioned it). This seems to be the resistor responsible for attack time. Correct me if I'm wrong though, but swapping it for 560R is going to make the attack FASTER?
- Limiter is where things start sounding really bad. The issue seems to be with the attack set to FAST. When it is at fast position everything sounds really distorted (horrible) especially in the low end. This seem to gradually disappear with increasing limiter recovery time. It is really pronounced and heavily distorted at 50 and 100ms settings, but starts to go away gradually at 200ms and up.
- with the attack switched to SLOW things sound somewhat grainy only at 50ms. The original 33609 I had over the weekend seemed to behave similarly in this scenario. When recovery switched to 100ms and up things sound smoother (normal).
- how to measure (fairly precisely) compressor/limiter response and recovery times in milliseconds? How to make the slopes visual on the analog scope without any special equipment?
PS: swapped R10 from 6k8 to 24k - seems to have solved the issue of the compressor sounding grainy at 100ms recovery.
Igor, thanks for your help man! I think I'm very close to have solved all of the issues with my unit (half of which are probably my misunderstandings of electronics and not knowing tolerances of calibration ) =)[/code]
Guys, please, slow!!!!!
Overloaded with my stuff, can't think so quick
Hehe... a little trick.
My Boonton 1120 has a S/N measurement mode.
In this mode, it puts approx. 1 sec of sinewave at output than 2 sec of sielence. Putting threshold about 10 db of compression...
Hooking digital scope to CV and triggering some samples before.....
In other words, kinda tone burst method....
Possible to make tone burst signal with PC...
Just put 0.5 sec of sinewave at 0 output, the sielence, repeat....
With analog scope, it is a bit hard to trigger the attack.
Try to put second channel to input of compressor and trigger from second chan. With high brightness possible to see what happens.
There's some definitions of attack and release time...
Can be measured at 63% or 100% of gain reduction.
In LA-2 for example there's light effect memory of photocell,
than, manual shows 63%....anyway...
BTW, feedback compressor's timing can vary from amount of
gain reduction.
There's some schemo versions...Mine shows 680R.
Actually, possible to put there 5k pot to change comp's attack time.
24k....
I copy-pasted everything from original old schemo.
And yes, 560r/680r, or 6k8/24k issues.
Overloaded with my stuff, can't think so quick
Hehe... a little trick.
My Boonton 1120 has a S/N measurement mode.
In this mode, it puts approx. 1 sec of sinewave at output than 2 sec of sielence. Putting threshold about 10 db of compression...
Hooking digital scope to CV and triggering some samples before.....
In other words, kinda tone burst method....
Possible to make tone burst signal with PC...
Just put 0.5 sec of sinewave at 0 output, the sielence, repeat....
With analog scope, it is a bit hard to trigger the attack.
Try to put second channel to input of compressor and trigger from second chan. With high brightness possible to see what happens.
There's some definitions of attack and release time...
Can be measured at 63% or 100% of gain reduction.
In LA-2 for example there's light effect memory of photocell,
than, manual shows 63%....anyway...
BTW, feedback compressor's timing can vary from amount of
gain reduction.
That's strange...please more info.
There's some schemo versions...Mine shows 680R.
Actually, possible to put there 5k pot to change comp's attack time.
24k....
I copy-pasted everything from original old schemo.
And yes, 560r/680r, or 6k8/24k issues.
:grin:
@underthebigtree:
If unit is calibrated to unity gain with no makeup, CV=0,
then, applying CV=3V, it should attenuate audio by 8 db.
Maybe...check if meter is 1mA. There's 2 pots, one for adjustment of
VCA (RV2), one for adjusting meter (RV3)...
Turn down rv3, should work. No need for 3k6 resistor.
@ wassx
If unit is calibrated to unity gain with no makeup, CV=0,
then, applying CV=3V, it should attenuate audio by 8 db.
Maybe...check if meter is 1mA. There's 2 pots, one for adjustment of
VCA (RV2), one for adjusting meter (RV3)...
Turn down rv3, should work. No need for 3k6 resistor.
@ wassx
Ladies and Gentlemen!
You see what happens!!!!! BTW, why, WHY Pat Metheny Secret Story
does not exists on vinyl?????? Ahhhhh....
All test proc is OK?
:guinness: :sam: :guinness: :sam:
:LAFROAIG:
:green:
Depending on ratio.
Yes, this can be sometimes freaky point. BC441's have different beta's
etc. I prefer to adjust threshold by putting it to 0 and feeding 0db when it just starts to compress, than same with -20.
Just get as close as possible. If compressor seems to have too high ratio
put 441's with lower beta. and vise versa.
Yes. See tolerances. In your case, adjust +4 for +3.7...this will compensate the drift.
Yes. You charging the cap' with less current (slower attack), so, nuff
unexpected.
Yap, answered
Thank you, I think there'll be some people who will ask same questions and....using "search" will find the answers
Good luck!
promixe
Well-known member
GEF24468 catalog number on german label Geffen... Limited edition 1992 LP =) It DOES exist =) Just VERY hard to find... I might know some people who have them here in the US =)
I didn't entirely get that... Those are the compressor section issues, I don't think they relate to the limiter section... I don't know what the next step should be to get rid of the limiter distortion/graininess...
creativeblue
New member
Hey guys can someone please help me with my transformer problem...
I have here 2 x LO2567, 2 x LI 10468 and 2 x LI 10368
is it possible to
1.) use the 10368 instead of the 31267 for interstage
and
2.) use the LO2567 instead of the L1173 for output?
Does it make sense, I mean would you recommend this, or should I better buy the right ones?
AND, how to connect them all?
thanks
I have here 2 x LO2567, 2 x LI 10468 and 2 x LI 10368
is it possible to
1.) use the 10368 instead of the 31267 for interstage
and
2.) use the LO2567 instead of the L1173 for output?
Does it make sense, I mean would you recommend this, or should I better buy the right ones?
AND, how to connect them all?
thanks
No, I meant the difference beetween schematics, right one is
placed on AMS website.
Regarding the limiter, check everything on front pannel pcb, maybe there's an error on recovery related components....
31267 used here as 2:1 line input trafo, not interstage.
10368 is 5k:2k4... Unpredictable.
Right trunny is 10468, it is most hard to get one...so,
I'd recommend to buy missing stuff from net.
With some riscue. 1173 used in +8 db connection.
2567 can be used in+4 db connection..
RV1 has only 2...3 db spare gain.
Right answer "no", but with the change of resistor's nominals on gain
make-up switch, possible.
There was some stuff on this tread. Search.
RTFM, or search.
(Neve trafo info at Dan Alexander's website for example)
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